Background: Vitamin D deficiency has been linked to aggravated juvenile idiopathic arthritis [JIA] activity.
Aim: This study aimed to evaluate the levels of serum 25[OH] Vitamin D in children with JIA. In addition to investigate the correlation of Vitamin D with the disease activity and used medication.
Subjects and Methods: Thirty-Nine children with confirmed diagnosis of JIA and 28 apparently healthy children were included in the current study. All were clinical evaluated in a systematic manner. The Juvenile Arthritis Disease Activity Score 71 [JADAS-71] was used to assess the disease activity. Serum 25[OH]D was evaluated using a direct, competitive electrochemiluminescence immunoassay. In addition, other routine laboratory work-up were done.  
Results: Patients with JIA exhibited a significantly lower levels of 25[OH]D than the controls [21.2 ± 7.4 vs 30.6 ± 10.9 ng/ml; p < 0.001]. Patients with active disease also had lower values than those with non-active disease [16.9 ± 8.7 ng/ml, vs 25.6 ± 7.4 ng/ml; p < 0.005]. VitD₃ levels showed a significant negative correlation with daily systemic corticosteroid [SCS] [r = -0.491, P = 0.005]. otherwise, no other significant results were reported.
Conclusion: Vitamin D seems to play a significant role in JIA as it was significantly reduced in patients with JIA. In addition, active form recorded more reduction. Furthermore, serum vitamin D levels had a negative correlation with disease activity and daily corticosteroid dosages.